Composite articles are typically composed of two primary components: a continuous resin matrix, and reinforcing fibers. Such composite articles are often required to perform in demanding environments, like aerospace and automotive applications, and therefore their physical and thermal limits and characteristics are of critical importance.
Phenolic resins are well known for use as a resin in the production of composite articles because of their excellent fire, smoke and toxicity (FST) properties, good chemical resistance, moderately low needed cure temperatures/times, and acceptable physical properties. However, they are also known to be quite difficult to process due to their high viscosities, and high porosity content. Also toxicity issues can be of concern.
Recently, benzoxazine compounds and compositions thereof have been employed to produce prepregs, laminates and structural composites via impregnating and infusion processes (see, for e.g. U.S. Pat. Nos. 4,607,091; 5,200,452; 6,207,786; WO 2005/019291; WO 2006/035021; WO2007/064801; and WO 2010/031826). These compounds and compositions exhibit improved handling and curing properties, such as, low viscosity, no volatile release during cure, near zero shrinkage, high glass transition temperature, excellent chemical and electrical resistance and flame retardancy. However, these benzoxazine compounds are typically latent materials; therefore, they require high temperatures to gel and cure. It would therefore be desirable to develop an alternative benzoxazine based composition that can be cured relatively quickly, at temperatures lower than those used conventionally, yet still exhibit excellent handling and curing properties so that it may be used in forming composite articles employed in demanding environments.